diff options
Diffstat (limited to 'rustversion/src/lib.rs')
| -rw-r--r-- | rustversion/src/lib.rs | 254 |
1 files changed, 0 insertions, 254 deletions
diff --git a/rustversion/src/lib.rs b/rustversion/src/lib.rs deleted file mode 100644 index cf8ed21..0000000 --- a/rustversion/src/lib.rs +++ /dev/null @@ -1,254 +0,0 @@ -//! This crate provides macros for conditional compilation according to rustc -//! compiler version, analogous to [`#[cfg(...)]`][cfg] and -//! [`#[cfg_attr(...)]`][cfg_attr]. -//! -//! [cfg]: https://doc.rust-lang.org/reference/conditional-compilation.html#the-cfg-attribute -//! [cfg_attr]: https://doc.rust-lang.org/reference/conditional-compilation.html#the-cfg_attr-attribute -//! -//! <br> -//! -//! # Selectors -//! -//! - <p style="margin-left:50px;text-indent:-50px"> -//! <b><code>#[rustversion::stable]</code></b> -//! —<br> -//! True on any stable compiler. -//! </p> -//! -//! - <p style="margin-left:50px;text-indent:-50px"> -//! <b><code>#[rustversion::stable(1.34)]</code></b> -//! —<br> -//! True on exactly the specified stable compiler. -//! </p> -//! -//! - <p style="margin-left:50px;text-indent:-50px"> -//! <b><code>#[rustversion::beta]</code></b> -//! —<br> -//! True on any beta compiler. -//! </p> -//! -//! - <p style="margin-left:50px;text-indent:-50px"> -//! <b><code>#[rustversion::nightly]</code></b> -//! —<br> -//! True on any nightly compiler or dev build. -//! </p> -//! -//! - <p style="margin-left:50px;text-indent:-50px"> -//! <b><code>#[rustversion::nightly(2019-01-01)]</code></b> -//! —<br> -//! True on exactly one nightly. -//! </p> -//! -//! - <p style="margin-left:50px;text-indent:-50px"> -//! <b><code>#[rustversion::since(1.34)]</code></b> -//! —<br> -//! True on that stable release and any later compiler, including beta and -//! nightly. -//! </p> -//! -//! - <p style="margin-left:50px;text-indent:-50px"> -//! <b><code>#[rustversion::since(2019-01-01)]</code></b> -//! —<br> -//! True on that nightly and all newer ones. -//! </p> -//! -//! - <p style="margin-left:50px;text-indent:-50px"> -//! <b><code>#[rustversion::before(</code></b><i>version or date</i><b><code>)]</code></b> -//! —<br> -//! Negative of <i>#[rustversion::since(...)]</i>. -//! </p> -//! -//! - <p style="margin-left:50px;text-indent:-50px"> -//! <b><code>#[rustversion::not(</code></b><i>selector</i><b><code>)]</code></b> -//! —<br> -//! Negative of any selector; for example <i>#[rustversion::not(nightly)]</i>. -//! </p> -//! -//! - <p style="margin-left:50px;text-indent:-50px"> -//! <b><code>#[rustversion::any(</code></b><i>selectors...</i><b><code>)]</code></b> -//! —<br> -//! True if any of the comma-separated selectors is true; for example -//! <i>#[rustversion::any(stable, beta)]</i>. -//! </p> -//! -//! - <p style="margin-left:50px;text-indent:-50px"> -//! <b><code>#[rustversion::all(</code></b><i>selectors...</i><b><code>)]</code></b> -//! —<br> -//! True if all of the comma-separated selectors are true; for example -//! <i>#[rustversion::all(since(1.31), before(1.34))]</i>. -//! </p> -//! -//! - <p style="margin-left:50px;text-indent:-50px"> -//! <b><code>#[rustversion::attr(</code></b><i>selector</i><b><code>, </code></b><i>attribute</i><b><code>)]</code></b> -//! —<br> -//! For conditional inclusion of attributes; analogous to -//! <code>cfg_attr</code>. -//! </p> -//! -//! <br> -//! -//! # Use cases -//! -//! Providing additional trait impls as types are stabilized in the standard library -//! without breaking compatibility with older compilers; in this case Pin\<P\> -//! stabilized in [Rust 1.33][pin]: -//! -//! [pin]: https://blog.rust-lang.org/2019/02/28/Rust-1.33.0.html#pinning -//! -//! ``` -//! # trait MyTrait {} -//! # -//! #[rustversion::since(1.33)] -//! use std::pin::Pin; -//! -//! #[rustversion::since(1.33)] -//! impl<P: MyTrait> MyTrait for Pin<P> { -//! /* ... */ -//! } -//! ``` -//! -//! Similar but for language features; the ability to control alignment greater than -//! 1 of packed structs was stabilized in [Rust 1.33][packed]. -//! -//! [packed]: https://github.com/rust-lang/rust/blob/master/RELEASES.md#version-1330-2019-02-28 -//! -//! ``` -//! #[rustversion::attr(before(1.33), repr(packed))] -//! #[rustversion::attr(since(1.33), repr(packed(2)))] -//! struct Six(i16, i32); -//! -//! fn main() { -//! println!("{}", std::mem::align_of::<Six>()); -//! } -//! ``` -//! -//! Augmenting code with `const` as const impls are stabilized in the standard -//! library. This use of `const` as an attribute is recognized as a special case -//! by the rustversion::attr macro. -//! -//! ``` -//! use std::time::Duration; -//! -//! #[rustversion::attr(since(1.32), const)] -//! fn duration_as_days(dur: Duration) -> u64 { -//! dur.as_secs() / 60 / 60 / 24 -//! } -//! ``` -//! -//! <br> - -extern crate proc_macro; - -mod attr; -mod bound; -mod date; -mod expr; -mod rustc; -mod time; -mod version; - -use crate::attr::Then; -use crate::expr::Expr; -use proc_macro::TokenStream; -use proc_macro2::{Ident, Span, TokenStream as TokenStream2}; -use quote::quote; -use syn::{parse_macro_input, ItemFn, Result}; - -#[proc_macro_attribute] -pub fn stable(args: TokenStream, input: TokenStream) -> TokenStream { - cfg("stable", args, input) -} - -#[proc_macro_attribute] -pub fn beta(args: TokenStream, input: TokenStream) -> TokenStream { - cfg("beta", args, input) -} - -#[proc_macro_attribute] -pub fn nightly(args: TokenStream, input: TokenStream) -> TokenStream { - cfg("nightly", args, input) -} - -#[proc_macro_attribute] -pub fn since(args: TokenStream, input: TokenStream) -> TokenStream { - cfg("since", args, input) -} - -#[proc_macro_attribute] -pub fn before(args: TokenStream, input: TokenStream) -> TokenStream { - cfg("before", args, input) -} - -#[proc_macro_attribute] -pub fn not(args: TokenStream, input: TokenStream) -> TokenStream { - cfg("not", args, input) -} - -#[proc_macro_attribute] -pub fn any(args: TokenStream, input: TokenStream) -> TokenStream { - cfg("any", args, input) -} - -#[proc_macro_attribute] -pub fn all(args: TokenStream, input: TokenStream) -> TokenStream { - cfg("all", args, input) -} - -fn cfg(top: &str, args: TokenStream, input: TokenStream) -> TokenStream { - match try_cfg(top, args, input) { - Ok(tokens) => tokens, - Err(err) => TokenStream::from(err.to_compile_error()), - } -} - -fn try_cfg(top: &str, args: TokenStream, input: TokenStream) -> Result<TokenStream> { - let args = TokenStream2::from(args); - let top = Ident::new(top, Span::call_site()); - - let mut full_args = quote!(#top); - if !args.is_empty() { - full_args.extend(quote!((#args))); - } - - let expr: Expr = syn::parse2(full_args)?; - let version = rustc::version()?; - - if expr.eval(version) { - Ok(input) - } else { - Ok(TokenStream::new()) - } -} - -#[proc_macro_attribute] -pub fn attr(args: TokenStream, input: TokenStream) -> TokenStream { - let args = parse_macro_input!(args as attr::Args); - - match try_attr(args, input) { - Ok(tokens) => tokens, - Err(err) => TokenStream::from(err.to_compile_error()), - } -} - -fn try_attr(args: attr::Args, input: TokenStream) -> Result<TokenStream> { - let version = rustc::version()?; - - if !args.condition.eval(version) { - return Ok(input); - } - - match args.then { - Then::Const(const_token) => { - let mut input: ItemFn = syn::parse(input)?; - input.sig.constness = Some(const_token); - Ok(TokenStream::from(quote!(#input))) - } - Then::Attribute(then) => { - let input = TokenStream2::from(input); - Ok(TokenStream::from(quote! { - #[cfg_attr(all(), #then)] - #input - })) - } - } -} |